After years of sporadic and superficial contact with their biological father, following a specific incident several months ago, my child has decided they no longer want to be in contact with him. They have not been responding to any messages (of which there have not been many) but recently turned 16 and he sent them a letter (hidden in a birthday card) full of vile comments (directed towards my child) and untruths (mostly about me - don't much care about this except it goes to show how delusional he is as some things are blatantly made up even though he seems to believe them himself, and others are perverted twists of the truth) as apparently "they are old enough to be told". I have never told my child anything about the relationship as I have never wanted to influence their own relationship which I have always facilitated.
I am unsure of the intention of the letter, as what it has done is only to ensure there is no way back to any sort of relationship. My child has now blocked him on their phone, after which he has gotten family members to message on their birthday with more of the same (now also blocked). Who does such a thing to a child that they supposedly care about, on their birthday no less?!
However, he has also approached my child's school, "wishing to discuss them." The previous incident was the first time he had been in contact with the school, despite the child being there many years and him being aware of the school they attend, as he has never shown an interest. But he has shown them he has PR by way of the child's birth certificate so the school is legally bound by this. School is aware of the situation and will only provide the information that is legally required, but unfortunately this includes information about events that parents can attend. My child does not want to see him and is scared he might turn up at school.
Sorry if I am being quite vague and rambling as I do not want to give too many specifics, but what can I do? I would get legal advice but don't even know where to start. If this was a peer of my child it would be called harassment and I am sure steps could be taken to protect them.
If it matters, he was and continues to be abusive to me. I will only communicate by text and will only answer if there is something to be said which mostly means ignoring his texts. In the last few years when there was contact this was arranged between himself and my child as they are old enough to sort this but they have now chosen not to engage in any communication and, as they are still a child, I need to step in and protect them, only I don't know how.
Please help with any advice or a point in the right direction.